This invention relates generally to conveyors and is particularly concerned with a new and improved power and free conveyor having a slow down section.
Conveyors are used in a multitude of industrial applications for conveying articles. In many of these applications the articles are conveyed by means of a drive chain which operates at a constant speed. In certain applications, however, it is advantageous for the conveyance speed of the articles to be reduced from the nominal speed along a certain section of the line. One way, obviously, of reducing the speed is to slow down the entire conveyor line. This, however, results in inefficiencies and wastefulness because the entire line is slowed down to accommodate the needs of only a limited section of the line. Moreover, the acceleration and deceleration forces impose increased loading on the conveyor in addition to wasting energy and impairing efficiency.
The present invention is directed to a new and improved conveyor having a slow down section which functions to slow down conveyed articles without the necessity of slowing down the main conveyor drive which conveys the articles at the nominal line speed over other sections of the line. With the present invention, the waste and inefficiencies referred to above are avoided. Furthermore, the slow down section can be operated from the same prime mover drive as the main conveyor drive chain through a use of a suitable drive reduction. The invention is also advantageous in that apart from the drive, there are no further electric components, nor are there any pneumatic or hydraulic components required for the slow down section.
The slow down section comprises an endless auxiliary chain which travels forwardly coextensive with a portion of the main drive chain but at a reduced speed from the main drive chain. Stops mounted on the auxiliary chain are operable to active positions to stop articles relative to the auxiliary chain so that the articles are decelerated from the speed imparted to them by the main drive chain to the lesser speed of the auxiliary chain. In the preferred embodiment, the stops are pivotally mounted in imbalance on the auxiliary chain and during their forward motion are biased by force of gravity to their active positions where they can engage the articles by abutment. Each stop further includes a roller which rides on a rail which runs alongside the auxiliary chain, thereby defining the active position for each stop. At the forward turn-around of the auxiliary chain, the imbalance of each stop is such that the stop would tend to pivot in relation to the auxiliary chain. However, as the stop traverses the forward turn-around, the roller continues to engage a circularly contoured arcuate continuation of the rail which is concentric with the circular arcuate path of travel of the chain at the turn-around. This serves to position the stop in relation to the auxiliary chain as it traverses the turn-around so that as the turn-around is completed the returning chain picks up the stop to support it in an inactive position during return travel to the rear turn-around. As the inactive stop traverses to the rear turn-around, it reaches a point where gravity becomes effective to pivot the stop to the active position in anticipation of its imminent entry into the path of travel of the articles.
The stops are furthermore arranged on the auxiliary chain such that if there is an article which overlies an individual stop when that stop begins to enter the path of travel of the articles, then the presence of such an overlying article is effective to return the stop to the inactive position. For this purpose a further roller is provided on each stop which, as the stop begins to enter the path of travel of the articles, is adapted to abut an overlying article. If the overlying article is being conveyed forwardly at the speed of the main drive chain, then the roller rolls, minimizing the frictional impact which would otherwise occur and hence, allowing the article to continue in its travel at the speed of the main drive chain. If the overlying article had already been slowed down by a preceding stop, then there would be no relative movement between a new stop and the article; however, the article is effective to return the new stop to the inactive position.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and chains which should be considered in conjunction with the accompanying drawings.
The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time for carrying out the invention.